Gas generators of this type are either solid propellant generators or so-called hybrid generators having a combustion chamber with solid propellant and with compressed gas. When it is activated electrically, the igniter generates hot gas and particles which ignite the pyrotechnic charge in the combustion chamber. Usually, the pyrotechnic solid propellant bed consists of a loose, i.e. random fill of small solid propellant tablets. The propellant bed is ignited from one side, and the resulting gas then flows through the part of the solid propellant which is not yet ignited, which more or less impedes the outflow of the resulting gas. A holding back of the gas can occur particularly in combustion chambers which are elongated and are ignited from one end side, i.e. combustion chambers with a small cross-section in relation to their length. This is spoken of here in terms of a so-called “jamming”, in which the generated gas can not be carried off quickly enough. Furthermore, after-burning phenomena can occur. The gas accumulation can also lead to the compacting of the tablets and to a fracture of individual tablets, so that during the igniting, a compacting takes place of the propellant which is not yet ignited, which further intensifies the above effects. Therefore, a slower burning of the propellant is caused, owing to the smaller surface, so that the rise in pressure of the outflowing gas can be negatively influenced. The reproducibility of the pressure curve, with respect to the gas flowing out from the gas generator, is made difficult.
EP 0 997 356 B1 or U.S. Pat. No. 5,882,036 therefore propose additionally incorporating a filter-like spacer between the inner side of the combustion chamber wall and the propellant bed, which spacer is spaced radially from the inner side of the combustion chamber wall and provides for outflow channels. The gas which is being produced can flow quickly via these channels to other regions of the propellant charge and ignite them, or the gas can also flow out quickly without hindrance through the remaining propellant via the channels.
The expenditure for such a construction is to be reduced by the invention, because the cylindrical filter elements must be relatively stable in construction, so as not to be pressed radially outwards against the inner side of the combustion chamber wall and so as not to constrict or close the channels in the case of the pressure which is produced.